WIS would have the tests and pin mumbers used to measure current/resistance at idle and high idle at the ECU harness. There are +/- 60 pins. The test is more involved than just measuring voltage to the transducer; will go into measuring vacuum output at the vac pump under other variables, etc. It will be 6 or 8 if this, then thats.

I don't have the tests.

Kartek (Evan) could tell you at what point the EGR opens and closes and what the ECU monitors. He disected this system.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Here's the EGR schedule from a 2007 posting by ScottMcPhee:

The exhaust gases are recirculated in line with the map stored in the IFI control module (N3/7) as soon as the following criteria are met:

* Coolant temperature between 60 °C and 110 °C
* Battery voltage 11 - 14 V
* Engine speed < 3000 rpm
* Fuel rack travel < 9 mm

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

These were my two questions:

"1. Any way I can get a look inside the valve to determine whether it is stuck open without taking the IM off?

2. I had asked before is there any chance the transducer electrical connection could be the problem and if so, how would I check?"

Still no answer to #1?

Re.#2, Based on replies, sounds like due to involvement of verifying a healthy transducer electrical feed, I should just proceed to pull IM to get at EGR valve, then open valve to see if it is stuck?

thanks

Sorry for the delay, haven't been on here for awhile. We disabled the EGR's on both our '98 and '99 (identical as regards this issue). The wiring referenced in the "how to" thread is under the black plastic cover, under the hood on passenger side at base of windshield. If you jack up the car, remove the belly pans, remove the aluminum charge air pipe (from the intercooler to the EGR housing) you might be able to look up into the EGR housing to see if the valve is stuck. At that point you might just as well take the manifold off since it's just those 20 or so torx bolts along the head, a really annoying clamp where the EGR pipe attaches to the EGR housing, and couple of vacuum lines.

If I remember correctly, our cars go into limp mode if this particular code is tripped. Much reduced power and speed, higher shift points, etc. I'm surprised that doesn't happen to yours.

Thanks Fred for the info. Believe someone had mentioned the limp mode before as a result of the EGR fault. My passing gear (turbo kick) defintely has been effected but I easily cruise at 80mph on interstate. Don't notice any difference in shift points or any other differences.

Re.#2, Based on replies, sounds like due to involvement of verifying a healthy transducer electrical feed, I should just not worry about that now and proceed to pull IM to get at EGR valve, then open valve to see if it is stuck? If valve isn't stuck, what do I check for?

thanks

Afraid I'm not much help besides what I've already suggested. The EGR valve itself is really simple - Just a vacuum diaphragm (follow the tube from the transducer) that pushes or pulls a little plunger to open a passage for the exhaust to flow into the EGR housing, which is bolted to the bottom of the intake manifold. I suppose the valve could be stuck open but I don't know for a fact that this would cause a code. There's a huge difference in performance when our cars are in limp mode but they've both been chipped so maybe the difference - limp versus normal operation - is greater. With the electronics defeated we gutted the EGR housings, plugged the holes, and removed the EGR pipe that runs around the back of the engine from the exhaust manifold to the EGR housing. Once you've had the manifold off you'll be an expert and find you can r/r it in no time. I suggest you soak all the glow plugs with PB blaster or similar while you've got access. Anything to help avoid having one stick/break is a good thing...trust me !

Had a thought. Can you think of any acess point on the EGR where I could get in with a shot of PB Blaster before pulling the IM, to hopefully loosen things up, how about where that vacum tube attaches to the EGR?

Do you suggest that I have new gaskets on hand when I pull the IM, plus any others?

"they've both been chipped"? are you referring to your wiring re-vamp?

Since the car is relatively new to me (about 150K miles) and I don't know how long ago the Glow Plugs were replaced, although all seem ok, probably would be smart to replace them. If I don't, guess it's still smart to give them a squirt? Any thoughts on what to replace them with?

The search must be for P0400 = P zero four zero zero

Q #1 - You could disconnect the charge air pipe form below and look up inside with a light. Wont be very rewarding.

Search Po400 too = P oh four zero zero

After you pull the IM you will probably find everything is pretty gunked up with greasy soot. Took me an hour to take things apart and 6 hours to clean it. i wouldn't mess with your GP's unless one is bad. Why tempt fate and snap one off that works?

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

P0400 = EGR flow mulfunction: issues link thread
P0400 = EGR flow mulfunction: issues link thread

..and I wouldn't change any glow plugs or even try to loosen them, just spray some PB Blaster, etc. at the threads while you have access. Couldn't hurt. Really only two gaskets involved - the intake manifold gasket and the square gasket with a bolt in each corner that goes between the intake manifold and the EGR housing. Both are rubber coated metal and should be replaced - as all gaskets should but of course gaskets are often re-used with success. I really don't think you'll accomplish anything by just trying to look. It'll be black and gunked up inside even if the EGR is working. Don't spray into the vacuum tube or its connection. That will just put whatever you spray all over the rubber diaphragm. No access to the moving shaft of the egr valve itself from that side. Review the links that whunter posted to be sure you've exhausted all other options first.